CVE-2019-19589
📋 TL;DR
The Lever PDF Embedder plugin 4.4 for WordPress fails to block polyglot PDF/JAR files, potentially allowing attackers to distribute malware disguised as PDFs. This affects WordPress sites using the vulnerable plugin version. Note that the vulnerability's validity is disputed since the plugin doesn't control file uploads.
💻 Affected Systems
- Lever PDF Embedder WordPress Plugin
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Attackers could upload malicious JAR files disguised as PDFs, leading to remote code execution or malware distribution when users download and execute the files.
Likely Case
Limited impact since the plugin only serves files and doesn't control uploads; attackers would need to bypass WordPress core upload restrictions first.
If Mitigated
Minimal impact if WordPress core file upload restrictions are properly configured and users don't manually rename downloaded files.
🎯 Exploit Status
Exploitation requires: 1) Uploading polyglot file through WordPress (may require authentication), 2) Users downloading and manually renaming file to .jar extension, 3) User executing the JAR file.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 4.5 and later
Vendor Advisory: https://wordpress.org/plugins/pdf-embedder/#developers
Restart Required: No
Instructions:
1. Log into WordPress admin panel. 2. Navigate to Plugins → Installed Plugins. 3. Find 'PDF Embedder' and click 'Update Now'. 4. Verify version is 4.5 or higher.
🔧 Temporary Workarounds
Disable PDF Embedder Plugin
allTemporarily disable the vulnerable plugin until patched
wp plugin deactivate pdf-embedder
Restrict File Uploads
allConfigure WordPress to block .jar files and polyglot files at upload
Add to wp-config.php: define('ALLOW_UNFILTERED_UPLOADS', false);
🧯 If You Can't Patch
- Implement strict file upload validation at WordPress level to block polyglot files
- Educate users not to rename downloaded files and to verify file extensions before execution
🔍 How to Verify
Check if Vulnerable:
Check WordPress admin → Plugins → PDF Embedder version. If version is exactly 4.4, system is vulnerable.Check Version:
wp plugin get pdf-embedder --field=versionVerify Fix Applied:
Verify PDF Embedder plugin version is 4.5 or higher in WordPress admin panel.📡 Detection & Monitoring
Log Indicators:
- WordPress upload logs showing PDF files with unusual headers
- Access logs showing requests for .pdf files followed by .jar requests
Network Indicators:
- Unusual file downloads with PDF MIME type but executable content
- Traffic patterns showing PDF downloads followed by JAR execution attempts
SIEM Query:
source="wordpress.log" AND ("upload" AND ".pdf") AND ("polyglot" OR "jar" OR "executable")